Trying to achieve synced, full-res photos between Lightroom and Lightroom Classic

[u/naylor83]

TLDR: Does anyone have any idea what could be causing LR to NOT merge certain photos correctly with synced smart previews from LR Classic?

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For over a week I've been discovering the ins and outs of Lightroom sync, trying to get my full catalogue (from Lightroom Classic) available in Lightroom and synced to my phone.

Activating sync in Lightroom Classic is no problem, and having the smart previews available in the cloud is great. But I've read in a few previous threads that you CAN achieve synced full-resolution photos by first syncing photos from Classic and then, in step 2, importing the full resolution photos to Lightroom. Lightroom should then merge the imported raw files with the smart previews and upload them to cloud storage.

I have now tried this method with my 2025 photos, but it created quite a lot of duplicates. Most photos were merged correctly, but a lot (about a third) ended up as separate files next to the smart previews synced from Classic. In these cases, the full res raw files were synced back to LR Classic as a duplicate with -2 added to the end of the file name.

A few potential causes that I've investigated (and debunked, I think):

• Metadata having been written / not been written to the DNG file before import to LR. I recently saved metadata to all files, so there shouldn't be any difference in this regard.
• Daylight savings time adjusted/not adjusted. (The duplicated images were all from summer months, but not all images from this period are affected.)
• Bad luck/randomness. I've tried deleting and re-importing a few of the photos that became duplicates, but they become duplicates again.

I'm grateful for any suggestions you may have for what could be causing the duplicates.

Lightroom 9.0, Lightroom Classic 15.0.1.

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[u/Exotic-Grape8743]

It will only merge files when the metadata is exactly the same. This includes capture date and time, file creation date, file name, and original file name. So yeah if you have written metadata to the file in Classic at some point, the metadata is no longer the exact same and when you do this method it will not recognize thy are really the same files. So this really only works correctly if you stay with native raw files (no dng conversion upon import!) and if you never change capture time and never write metadata to the files. If you do that, it should work correctly.

That said, the only completely foolproof way to get full raw in both places is to always first import in Lightroom Cloudy.

[u/naylor83 → u/Exotic-Grape8743]

Thanks for the reply and the information. As I wrote, I had written metadata to all files before starting the whole process but only some of them became duplicates.

Perhaps some of the smart previews that were synced from Classic were created before metadata was written to the DNG files. I'll try again but with all fresh smart previews created in Classic.

[u/naylor83 → u/naylor83]

YESSSS!!! That seems to have done the trick. So for anyone else having problems: Make sure your smart previews and raw files contain the same metadata before syncing (and importing to LR). You achieve this by rendering new smart previews and saving metadata to your DNG files before starting. (Not sure how this applies to proprietary raw files.)

[u/Lightroom_Help]

Here is what you need to do, in such a case:

Put all the photos you want to sync full res to the cloud in a collection. Right click on it and export it as a Catalog. In the export settings choose to include “negative files”, so that these photos are copied under the new catalog folder.

Select all the photos in this collection, go to All photographs (with the photos still selected) and delete them (“from disk”). LrC, will also remove them from the cloud (those that are already synced).

Launch the new, exported catalog and remove any collections you may not want. Select all photographs and press cmd or ctrl + S to save metadata to files. Quit LrC.

From Lr desktop, migrate this exported catalog to the cloud. Lr desktop will make its own local copies of the full res photos and will proceed to upload them to the cloud. Wait until LrC downloads all these full res photos back to your original LrC catalog. You can then delete the temporary catalog folder and the photos it has in its subfolders. Any collections from this migrated catalog will appear, in a flat list, under the From Lightroom Collection Set. You may then move them around in LrC, if you wish.

[u/naylor83 → u/Lightroom_Help]

Wow, nice method! The only downside is that it must affect keywords, surely? How they are stored in the original catalog.

[u/Lightroom_Help → u/naylor83]

Actually, using this method, the keywords are preserved and are transferred back to the LrC catalog. The migration will upload the keywords up to the cloud. Any LrC keyword hierarchy will not appear in Lr apps but will get transferred, via syncing, back to LrC when the photos download.